ACTION Syntax Reference

Actions are executable logic blocks triggered by events such as timed intervals, topic updates, or explicit calls. They are the primary way to implement automation in LoT.

Actions run inside the MQTT broker itself, eliminating the need for external middleware or application servers.

Basic Syntax

DEFINE ACTION <action_name>
ON <EVENT_TRIGGER>
DO
    <action_logic>

Components

action_name

string

required

A unique identifier for the action. Use descriptive names that indicate the action’s purpose (e.g., SensorDataProcessor, HeartbeatMonitor).

EVENT_TRIGGER

trigger

required

Specifies when the action executes. Can be time-based (ON EVERY, ON TIMESTAMP), topic-based (ON TOPIC), initialization (ON START), or omitted for callable actions.

action_logic

statements

required

One or more LoT statements that execute when the action triggers. These can include publishing, variable assignment, conditionals, and Python calls.

Action Structure

Every action follows this general structure:

DEFINE ACTION ActionName
ON <trigger_type> DO
    // Variable assignment
    SET "variable" WITH <value>
    
    // Conditional logic
    IF <condition> THEN
        // Statements
    ELSE
        // Alternative statements
    
    // Topic operations
    PUBLISH TOPIC "output/topic" WITH <payload>
    KEEP TOPIC "internal/topic" WITH <payload>

Trigger Types

Time-Based
Topic-Based
Callable

Execute at regular intervals:

DEFINE ACTION PeriodicTask
ON EVERY 5 SECONDS DO
    PUBLISH TOPIC "system/heartbeat" WITH "alive"

Supported units: SECOND(S), MINUTE(S), HOUR(S), DAY(S), WEEK(S)

Execute when a topic receives data:

DEFINE ACTION MessageProcessor
ON TOPIC "sensors/temperature" DO
    PUBLISH TOPIC "processed/temp" WITH PAYLOAD

Supports wildcards: + (single level), # (multi-level)

No trigger - called manually or by other actions:

DEFINE ACTION UtilityFunction
DO
    KEEP TOPIC "cache/data" WITH (GET TOPIC "source/data")

Invoked via: $SYS/Coreflux/Command with payload -runAction ActionName

Compatible Keywords

Keywords that can be used within action logic:

Variable Operations

Keyword	Description
`SET`	Create or assign a variable
`GET TOPIC`	Retrieve data from a topic
`GET JSON`	Extract fields from JSON payloads — see Working with JSON

// For topic "sensors/temp001/data": POSITION 1="sensors", POSITION 2="temp001", POSITION 3="data"
SET "sensor_id" WITH TOPIC POSITION 2
SET "temperature" WITH (GET TOPIC "sensors/temp" AS DOUBLE)
SET "humidity" WITH (GET JSON "humidity" IN PAYLOAD AS DOUBLE)

Topic Operations

Keyword	Description
`PUBLISH TOPIC`	Broadcast data to all subscribers
`KEEP TOPIC`	Store data internally (not broadcast)

PUBLISH TOPIC "output/data" WITH {temperature}
PUBLISH TOPIC "devices/" + {device_id} + "/status" WITH "online"
KEEP TOPIC "cache/last_reading" WITH PAYLOAD

Control Flow

Keyword	Description
`IF ... THEN ... ELSE`	Conditional execution

IF {temperature} > 80 THEN
    PUBLISH TOPIC "alerts/high_temp" WITH {temperature}
ELSE
    PUBLISH TOPIC "status/normal" WITH "OK"

Entities

Entity	Description
`PAYLOAD`	The data that triggered the action
`TOPIC POSITION n`	Extract segment from topic path
`TIMESTAMP`	Generate timestamps (UTC, UNIX)
`EMPTY`	Check if a topic has no data

Python Integration

Keyword	Description
`CALL PYTHON`	Execute Python functions

Extend LoT with Python: Use CALL PYTHON to execute complex calculations, data validation, or integrate external libraries. See the Python Integration guide for complete syntax and examples.

Type Casting

Use AS to cast values when performing comparisons or calculations:

GET TOPIC "sensors/value" AS DOUBLE
GET TOPIC "config/enabled" AS BOOL
GET TOPIC "settings/count" AS INT
GET JSON "temperature" IN PAYLOAD AS DOUBLE

Supported types: STRING, INT, DOUBLE, BOOL, TIMESTAMP

Complete Example

Putting It All Together: This example demonstrates topic extraction, JSON parsing, conditional logic, and publishing - the core patterns you’ll use in most actions.

DEFINE ACTION SensorDataProcessor
ON TOPIC "sensors/+/raw" DO
    // Extract sensor ID from topic (position 2 = the wildcard)
    // Topic: sensors/temp001/raw → POSITION 1="sensors", POSITION 2="temp001", POSITION 3="raw"
    SET "sensor_id" WITH TOPIC POSITION 2
    
    // Get the temperature value
    SET "temp_value" WITH (GET JSON "temperature" IN PAYLOAD AS DOUBLE)
    
    // Check thresholds
    IF {temp_value} > 80 THEN
        PUBLISH TOPIC "alerts/high_temp/" + {sensor_id} WITH PAYLOAD
    ELSE
        PUBLISH TOPIC "sensors/processed/" + {sensor_id} WITH PAYLOAD
    
    // Always update the last reading timestamp
    PUBLISH TOPIC "sensors/" + {sensor_id} + "/last_update" WITH TIMESTAMP "UTC"

Quick Start

Developing and Managing Coreflux

Coreflux MQTT Broker

LoT Language

Product Updates

Basic Syntax

Components

Action Structure

Trigger Types

Compatible Keywords

Variable Operations

Topic Operations

Control Flow

Entities

Python Integration

Type Casting

Complete Example

Next Steps

Action Triggers

Operations

​Basic Syntax

​Components

​Action Structure

​Trigger Types

​Compatible Keywords

​Variable Operations

​Topic Operations

​Control Flow

​Entities

​Python Integration

​Type Casting

​Complete Example

​Next Steps

Action Triggers

Operations

Basic Syntax

Components

Action Structure

Trigger Types

Compatible Keywords

Variable Operations

Topic Operations

Control Flow

Entities

Python Integration

Type Casting

Complete Example

Next Steps